lkml.org 
[lkml]   [2015]   [Jul]   [1]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: [PATCH RFC tip/core/rcu 5/5] rcu: Limit expedited helping to every 10 ms or every 4th GP
On Tue, Jun 30, 2015 at 02:48:30PM -0700, Paul E. McKenney wrote:
> From: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>

This seems like a good place to explain why this is a desirable thing,
no?

Why would you want to limit this?

> Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
> ---
> kernel/rcu/tree.c | 15 ++++++++++++---
> 1 file changed, 12 insertions(+), 3 deletions(-)
>
> diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c
> index 308b6acb4260..247aa1120c4c 100644
> --- a/kernel/rcu/tree.c
> +++ b/kernel/rcu/tree.c
> @@ -3505,10 +3505,19 @@ void synchronize_sched_expedited(void)
> !atomic_read(&rsp->expedited_need_qs));
>
> rcu_exp_gp_seq_end(rsp);
> - mutex_unlock(&rnp->exp_funnel_mutex);
> smp_mb(); /* ensure subsequent action seen after grace period. */
> - if (rsp->gp_kthread && rcu_gp_in_progress(rsp))
> - wake_up(&rsp->gp_wq);
> + if (rsp->gp_kthread && rcu_gp_in_progress(rsp)) {
> + static unsigned long nextgp;
> + static unsigned long nextjiffy;
> +
> + if (time_after_eq(jiffies, nextgp) ||
> + ULONG_CMP_GE(rsp->gpnum, nextgp)) {
> + nextgp = rsp->gpnum + 4;
> + nextjiffy = jiffies + 10;
> + wake_up(&rsp->gp_wq);
> + }
> + }
> + mutex_unlock(&rnp->exp_funnel_mutex);
>
> put_online_cpus();
> }
> --
> 1.8.1.5
>


\
 
 \ /
  Last update: 2015-07-01 12:21    [W:0.124 / U:1.200 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site